#6: added ability to pass custom dns servers to resolver (#7)

added ability to pass custom dns servers to resolver (it's important because exporter may be ran not in Russia while we still should use Russia resolvers)

Author: bissquit

README.md

@@ -43,6 +43,7 @@ PORT=8080 ; docker run -it --rm --name rkn-exporter \
   -e APP_DOMAINS=/app/inputs/domains.txt \
   -e APP_SUBNETS=/app/inputs/blocked_subnets.txt \
   -e APP_THREADS_COUNT=10 \
+  -e APP_DNS=8.8.8.8 \
   -e LOG_LEVEL=DEBUG \
   bissquit/rkn-exporter:latest
 ```
@@ -92,6 +93,7 @@ This command is not needed if you configure env with `make env`.
 |-d, --domains|`APP_DOMAINS`|Path to a file with domains to check. One domain per line (default: No)|
 |-s, --blocked_subnets|`APP_SUBNETS`|Path to a file with subnets bloked by RKN. One subnet per line. Or url with json list (default: No)|
 |-t, --threads_count|`APP_THREADS_COUNT`|Threads count to parallelize computation. Is useful when DNS resolving is slow (default: 10)|
+|--dns|`APP_DNS`|DNS servers (default: 8.8.8.8)|
 |-|`LOG_LEVEL`|Log level based on Python [logging](https://docs.python.org/3/library/logging.html) module. expected values: DEBUG, INFO, WARNING, ERROR, CRITICAL (default: INFO)|
 
 

docker-compose.yml

@@ -17,6 +17,7 @@ services:
       # rkn-exporter receives file or url
       - APP_SUBNETS=/app/inputs/blocked_subnets.txt
       - APP_THREADS_COUNT=10
+      - APP_DNS=8.8.8.8
       - LOG_LEVEL=DEBUG
     volumes:
       - ./inputs:/app/inputs

handler.py

@@ -270,3 +270,19 @@ async def data_handler(path: str) -> set:
         raw_data = read_file_to_list(path=path)
 
     return set(ip_converter(raw_data))
+
+
+def normalize_dns(dns_str: str) -> list:
+    # remove any whitespaces from string first then split string into a list
+    # comma is default delimiter
+    dns_servers_list = (dns_str.replace(' ', '')).split(',')
+
+    valid_list = []
+    for dns_server_str in dns_servers_list:
+        # check if string is a valid ipv4 address
+        if validators.ipv4(dns_server_str):
+            valid_list.append(dns_server_str)
+        else:
+            logger.debug(f'{dns_server_str} is not a valid ip address of DNS server!')
+    logger.debug(f'DNS server(s) to proceed: {valid_list}')
+    return valid_list

kubernetes/config.yaml

@@ -5,7 +5,7 @@ common:
   k8s_namespace: monitoring
 
   # type not only image tag but hash too
-  rkn_exporter_version: 'v1.3-dev@sha256:df72a1eb422ba07fc42686b0bc7198a4c953ddbbefe6ebb0a5c9469d70d24e59'
+  rkn_exporter_version: 'v1.6@sha256:65b475b4e3102f901f9d8d5aba1239bf18bc3e268009f6cf528f7d276fe73c14'
   # default settings. You may rewrite them for certain k8s cluster
   rkn_exporter:
     ip: "0.0.0.0"
@@ -14,6 +14,7 @@ common:
     domains: "/app/inputs/domains.txt"
     subnets: "https://reestr.rublacklist.net/api/v2/ips/json/"
     threads_count: "10"
+    dns: "8.8.8.8"
     log_level: "DEBUG"
 
 env-name:

kubernetes/templates/deployment.yaml.j2

@@ -31,14 +31,16 @@ spec:
               value: "{{ rkn_exporter.subnets }}"
             - name: APP_THREADS_COUNT
               value: "{{ rkn_exporter.threads_count }}"
+            - name: APP_DNS
+              value: "{{ rkn_exporter.dns }}"
             - name: LOG_LEVEL
               value: "{{ rkn_exporter.log_level }}"
           resources:
             requests:
-              cpu: 40m
+              cpu: 100m
               memory: 64Mi
             limits:
-              cpu: 80m
+              cpu: 200m
               memory: 128Mi
           volumeMounts:
             - name: inputs

rkn_exporter.py

@@ -13,7 +13,8 @@
     return_metrics, \
     fill_queue, \
     subnets_to_ips, \
-    data_handler
+    data_handler, \
+    normalize_dns
 
 # possibly it's good idea to use contextvars here
 data = 'rkn_computation_success 0'
@@ -52,6 +53,10 @@ def parse_args():
                         default=os.getenv("APP_THREADS_COUNT", 10),
                         type=int,
                         help='Threads count to parallelize computation. Is useful when DNS resolving is slow (default: 10)')
+    parser.add_argument('--dns',
+                        default=os.getenv("APP_DNS", '8.8.8.8'),
+                        type=str,
+                        help='DNS servers (default: 8.8.8.8)')
     return parser.parse_args()
 
 
@@ -97,8 +102,7 @@ async def handler(self):
         blocked_subnets_set = await data_handler(self.args.blocked_subnets)
         blocked_ips_set = subnets_to_ips(blocked_subnets_set)
 
-        # I'll add variables later
-        resolver = self.initialize_resolver(nameservers=['8.8.8.8'],
+        resolver = self.initialize_resolver(nameservers=normalize_dns(self.args.dns),
                                             timeout=20,
                                             lifetime=20,
                                             retry_servfail=False)

tests/test_handler.py

@@ -17,7 +17,7 @@
                     return_domain_metrics, \
                     read_file_to_list, \
                     validate_domains, \
-                    fill_queue, subnet_to_ips, subnets_to_ips, get_data, ip_converter, data_handler
+                    fill_queue, subnet_to_ips, subnets_to_ips, get_data, ip_converter, data_handler, normalize_dns
 
 
 # taken from https://github.com/aio-libs/aiohttp/blob/master/tests/test_resolver.py
@@ -282,3 +282,10 @@ async def test_data_handler(mocker):
     mocker.patch('handler.read_file_to_list', return_value=await mock_awaitable_obj(raw_ips_list))
     blocked_subnets_set = await data_handler('./fake/path/to/file')
     assert blocked_subnets_set == valid_subnets_set
+
+
+def test_normalize_dns():
+    input_str = '  8.8.8.8 ,8.8.4.4,  8.8.1.1111'
+
+    valid_dns_list = normalize_dns(input_str)
+    assert valid_dns_list == ['8.8.8.8', '8.8.4.4']